Arty computers

[Jim Leonard]

Chuck Guzis wrote:
> The same sort of behavior exhibits itself 
> on some of the x86 CPUs--where:
> 
> l1:
>     mov	al,ds:[si]
>     dec	cx
>     mov	es:[di],al
>     jnz		l1
> 
> runs about as fast as rep movsb (and, in cases, somewhat faster).  On 
> those same CPUs, replacing the dec cx/jnz with a loop instruction 
> will actually slow things down.

Could you clarify which 808x CPUs in particular you're referencing in 
the above?  There isn't a single case from 808x to 486 where that code 
will beat rep movsb.  Were you referring to Pentiums and higher?
-- 
Jim Leonard (trixter at oldskool.org)            http://www.oldskool.org/
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